This proposal will investigate the performance of a combined MRI-optical imaging system in diagnosis of breast cancer. A diffuse optical tomography (DOT) imaging system integrated with a 4.0 T MRI scanner will be used. It is hypothesized that the additional information measured by MR spectroscopy (Choline) and optical imaging (oxygen saturation and kinetics of indocyanine green ICG) will improve the specificity of DCE-MRI (dynamic contrast enhanced MRI) in diagnosis of breast cancer. The study is submitted responding to program announcement PAR-06-293, focusing on area-3 of research "clinical feasibility studies to demonstrate potential efficacy of promising discoveries in imaging technology", the technology in this proposal being the combined MRI-DOT system. High resolution anatomic MRI and DCE-MRI has evolved into an established clinical tool for detection and diagnosis of breast lesions in patients with dense breasts. The morphological appearance and enhancement kinetics are two essential elements. Due to its high sensitivity MRI is fast becoming the most popular imaging modality for screening young women who are susceptible to early development of breast cancer. Pre-operative MRI has also become a common procedure for detecting multifocal or multicentric diseases to facilitate surgical planning. However, despite its high sensitivity, MRI also detects many benign lesions. The low specificity may lead to great anxiety to patients, and many unnecessary biopsies or over-treatment. Other adjunct imaging modality to improve specificity is greatly needed. MR spectroscopy (MRS) and DOT are two techniques that have great potential to provide complementary information. In this study we will evaluate how these two modalities can enhance the performance of DCE-MRI in diagnosis of breast cancer. Subjects with suspicious breast lesions will be studied using the combined MRI-DOT system. Then ROC analysis using artificial neural network and conventional regression analyses will be used to assess sensitivity/specificity of the optimized morphological and kinetic parameters measured by DCE-MRI. Then the ROC curves using the optimized DCE-MRI parameters with addition of (1) Choline measured by MRS, (2) oxygen saturation, and (3) transport rates in ICG kinetics will be obtained to evaluate whether these additional information may be used to improve the diagnostic specificity. After the study is completed, we will be able to test the hypothesis that "additional information provided by MR Spectroscopy and optical imaging can be used in conjunction with morphological and kinetics parameters measured by DCE-MRI to improve diagnosis of breast cancer". Furthermore, we will be able to determine among the additional information measured by MRS and DOT, which parameter(s) are the most essential to design an optimized protocol. Although the current breast imaging modalities have achieved a high success, further improvements for a subpopulation of women in whom conventional imaging do not work well are in great need. Our goal is to develop an imaging technology with optimized acquisition protocol to improve diagnostic specificity of breast cancer, particularly for young women, so that they would not be subjected to false positive findings. [unreadable] [unreadable] [unreadable]